Wednesday, September 15, 2010

Report: Why bird flocks move in unison

Birders have long longed to understand how birds in flicks move in synchronicity and appear to make snap decisions as a group. Researchers from Budapest, Hungary, used a particle model to investigate flocks of birds landing on foraging flights.

In the report published in "New Journal of Physics," the researchers describe their use of a self-propelled particle system in whcih the particles represent birds with parameters like position and velocity. The scientists found that "the collective switching from the flying to the landing state overrides the individual landing intentions of each bird.

In the absence of a decision making leader, the collective shift to land is heavily influenced by perturbations the individual birds are subject to, such as the birds’ flying position within the flock. This can be compared to an avalanche of piled up sand, which would occur even for perfectly symmetric and cautiously placed grains, but in reality happens much sooner because of increasing, non-linear fluctuations.

The researchers said, “Our main motivation was to better understand something which is puzzling and out there in nature, especially in cases involving the stopping or starting of a collective behavioural pattern in a group of people or animals.

Possible applications include collectively flying, unmanned aerial vehicles, initiating a desired motion pattern in crowds or groups of animals and even finance, where the results could be used to interpret collective effects on selling or buying shares on the stock market.